1. Field of the Invention
The present invention relates to information transmission and reception in a communication system. More particularly, the present invention relates to a method and apparatus of measuring channels and transmitting a feedback regarding multiple beams formed for multiple users in a wireless communication system.
2. Description of the Related Art
To satisfy ever-increasing demands for wireless data traffic, wireless communication systems have been developed toward higher data rates. Previously, efforts were expended on increasing spectral efficiency in order to increase data rates. However, as demands for traffic have been accelerated due to increased demands for smartphones and tablet Personal Computers (PCs) and the resulting rapid growth of application programs requiring a large amount of traffic, satisfying the soaring demands for wireless data traffic simply by increasing spectral efficiency is difficult.
One approach to averting the problem associated with the soaring demands for wireless data traffic is to use a very broad frequency band. Because securing a broad frequency band in the frequency band below 5 GHz used for legacy cellular mobile communication systems is difficult, the broadband frequency should be obtained from a higher frequency band. However, as wireless communication is conducted in a higher transmission frequency, propagation path loss is increased. The resulting shortened propagation distance reduces service coverage. One technique to mitigate path loss and increase the propagation distance of waves is beamforming.
Transmission beamforming is a scheme that focuses signals transmitted from a plurality of antennas toward a specific direction (e.g., space). A set of plural antennas is called an array antenna and each antenna included in the array antenna is called an antenna element. Because of the advantages associated with an increased propagation distance and almost non-transmission of a signal in directions other than a specific direction, the transmission beamforming reduces interference with other users significantly.
Reception beamforming is available on the part of a receiver using a reception array antenna. The reception beamforming focuses wave reception toward a specific direction, thereby increasing the reception sensitivity of a signal from the specific direction and excluding signals from other directions. Therefore, interference signals are blocked.
The wavelength of a signal wave gets shorter in a higher transmission frequency. If antennas are configured at half-wavelength intervals, more antennas may be arranged in the same area in an array antenna. Beamforming is favorable to a high-frequency communication system because high-frequency beamforming can produce a higher antenna gain than low-frequency beamforming.
Therefore, a need exists for a method and apparatus of transmitting and receiving information in a communication system. For example, a need exists for a hybrid beamforming structure by combining analog beamforming with digital beamforming in order to achieve a high antenna gain.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present invention.